An example of a design rule check system used for a design of a wiring pattern of a printed wiring board and an IC (Integrated Circuit) package is disclosed in Japanese Patent Application Laid-Open No. 1991-118665. In a design rule check system described in Japanese Patent Application Laid-Open No. 1991-118665, wiring pattern information, wiring restriction information and substrate information is inputted, and a check result list and a not-connected section list are outputted. That is, the design rule check system reads design data of a printed wiring board, then, detects design data portions which do not satisfy a designated threshold value and generates contents thereof, for each design rule check item that has been designated as a design rule in advance, and indicates those as an error message.
In the design rule check system mentioned above, when the number of design rule check items is large, or when a threshold value designated in each design rule check item is severe, there occurs a lot of cases where the design data do not satisfy threshold values (hereinafter, referred to as an error). In this case, it is impossible to correct all errors actually, and it is difficult to reflect every result of design rule checks into the design of a wiring pattern.
However, among design rule check items, there exist “items to which error correction is indispensable” and “items that do not need error correction necessarily”.
As one of “items to which error correction is indispensable”, there is a design rule check item about a manufacturing rule, for example. When an error occurs about such design rule check item, a designer of a printed wiring board or an IC package has to correct the error certainly.
On the other hand, as one of “items that do not need error correction necessarily”, there is a design rule check item about EMI (Electro Magnetic Interference) reduction, for example. When an error occurs about such design rule check item, it is desired that the designer corrects the error as much as possible. For example, in design rule check items for EMI reduction, items having a high effectiveness for evading a EMI problem, and items having a low effectiveness for the problem are intermingled. A designer has to evaluate an effect when an error is corrected one by one on each of design rule check items that have the error, and then has to select a design rule check item to be corrected the error on the basis of the evaluation.